An ink jet recording apparatus discharges ink drops on a medium, such as paper, and forms an image and letters using the ink. The ink jet recording apparatus includes an ink jet head which discharges the ink drops according to an image signal.
The ink jet head includes nozzles that discharge ink drops, an ink pressure chamber that communicates with the nozzles, and a pressure generation element that generates pressure which causes ink in the pressure chamber to be discharged from the nozzles. A piezoelectric body is used as the pressure generation element. A piezoelectric element (also referred to as “piezo element” for short) converts a voltage into a force. In a case where the voltage is applied to the piezoelectric element, contraction, expansion, or shear deformation of the piezoelectric element occurs. Pressure is generated in the ink in a pressure chamber as a result of the deformation of the piezoelectric element. A lead zirconate titanate (PZT) is used as a representative piezoelectric element.
An ink circulation-type ink jet head is known. In the ink circulation-type ink jet head, ink stored in an ink tank external to the ink jet head is supplied to the above-described inkjet head, and a part of the ink is discharged from the nozzles. The ink, which is not discharged from the nozzles, is returned to the ink tank. The ink returned to the ink tank is supplied to the ink jet head again. In order to supply the ink, which is returned to the ink tank, to the ink jet head again, a pump is used. There is a case where the pump, which transports the ink, generates bubbles in the ink. If the bubbles included in the ink are supplied to the ink jet head, defective ink discharge may occur.